The present invention relates to an improved joint for a tension leg and particularly to a releasable latch for such joint which can be set and released by simple axial movement of the inner leg member.
In current operations offshore platforms are used which have buoyancy and are held in place by tension legs which are secured to a receptacle mounted on a template on the sea floor. It is inherent in such platforms that the legs which connect between the sea floor receptacle and the floating platform are maintained in tension to increase the stability of the platform. Such tension mooring has involved the use of cables, tubular members and solid members as the tension mooring elements. The present invention relates to an improved tension leg joint which allows quick and simple connection between connecting joint members and easy and positive release of the connecting latch mechanism by lowering the upper member.
U.S. Pat. No. 3,452,815 discloses a latching mechanism for connecting lines run from a floating vessel to a subsea well which includes latching dogs to coact with a circumferential groove in the post or mandrel and carried by and other member and including an actuator means to block the dogs in latched position and preset means including a the use of a weight dropped from the surface to engage and move the actuator to a latch releasing position. U.S. Pat. No. 4,651,818 discloses a tubing plug which is latched by dogs being cammed into an internal recess within the tubular member in which the plug is to seat. The cam is a sleeve sliding on the rod mandrel for locking and releasing the dogs from their latched position.
U.S. Pat. No. 4,611,953 discloses a tension leg platform tendon bottom connector. This structure provides a connection from a tubular tension leg tendon into the receptacle in the anchor template located on the sea floor. This connection includes dogs which are used to engage within an internal recess in the receptacle and keys which when lowered into the recess cause relative movement of the dogs to move then into an inactive position allowing removal of the tendon from the receptacle. This is accomplished because the dogs are mounted on a carrier sleeve and the keys are mounted from the body but in position to engage a ring connected to the carrier sleeve so that when the keys pass upwardly past the internal recess they move the carrier sleeve upwardly and the dogs are brought upwardly into retracted position so that the assembly may be retrieved from the receptacle. U.S. Pat. No. 4,451,056 discloses another underwater tension connector for use in an offshore mooring system.
U.S. Pat. No. 3,448,799 discloses a well completion unit which utilizes cam actuated locking dogs to provide the clamping connection between the Christmas tree and flowline in a subsea well.
U.S. Pat. No. 3,071,188 discloses the use of a ring having depending flexible latching fingers which engage within external grooves in a tubular member and when engaged a sleeve is moved into surrounding relationship to the exterior of the fingers to secure them in their latching position.